1. Field of the Invention
This invention relates to the measurement of heat transfer occurring at a surface, and is applicable particularly, but not exclusively, to the measurement of condensation heat transfer coefficients in nuclear reactors.
2. Description of Related Art
In the very unlikely event of a failure causing a loss of coolant in a pressurised water reactor, steam might be released into the vessel, resulting in a pressurised mixture of steam and air which could affect the operation of safety equipment in the vessel. The temperature response of affected equipment is dependent upon the local heat transfer coefficients, which, in turn, are dependent on the total pressure within the vessel, the magnitude of local gas velocities and the ratio of mass of air to mass of steam.
It is necessary to be able to measure heat transfer coefficients as a function of these three parameters.
Various devices and methods have previously been proposed for effecting such measurements. These have included measurement of the transient thermal response of solid metal bodies, but this provides only transient information. Heat flux meters have been embedded in the pressure vessel walls, but the positions of such meters are restricted. Measurements have also been carried out using water-cooled metal bodies, but the shape and dimensions of the condensing surface are limited. Furthermore, none of these known techniques allows adjustment of the surface temperature on which condensation takes place.